We all have difficult conversations everyday, be it with someone who steps in front of you in line or with your boss asking for a raise. Sometimes they don't end as we would have liked it, right?
How many times we think that the other party is to blame of the result? Well, that's normal, our self-conservation instinct does that to protect us of bad feelings. But that is not generally a good thing, because at the same time cancels any type of self analysis.
While you might be feeling better after making your assistant a hard time for forgetting to send an important letter that might have earned you a contract, that doesn't really solve your problem. You'll probably fire him without understanding what triggered his mistake, maybe you contributed somehow to this situation, most of the cases that is true.
These being said, I want to recommend to you an EXTRAORDINARY book exactly about how to handle a difficult conversation: Difficult Conversations: How to Discuss What Matters Most by a group of authors who work at the Harvard Negotiation Project. It seems we all react pretty much the same in similar situations, like when we have an argument with someone or when we give bad news. The book analyses all these things that stand behind our behavior during a difficult conversation. Of course, each ones situation and experience are different, but all of them can be improved if we keep in mind at least some of the advices in this book.
The book presents us a lot of practical situations exemplified with different fictional characters, first to identify the mistakes we do and second to improve the result of the conversation, for ALL the parties involved. Because in general everyone involved is right and wrong at the same time. And this happens mostly because we all judge what's around us by filtering it through our "universe" of thoughts, beliefs, experience, which are different of the ones of our partners in conversation.
While the content of the book can be resumed in different ways (I tried doing that with the mind map present at the bottom of the article), the biggest value have the situations lively described and in which I think you will also recognize yourself.